Well drilling apparatus



Dec. 3, 1963 w. CLARK ETAL WELL DRILLING APPARATUS 2 Sheets-Sheet 1 Filed March 5, 1959 I INVENTORS MLA/c5 (24e/z ,4A/v

Dec. 3, 1963 w. CLARK ETAL WELL DRILLING APPARATUS 2 Sheets-Sheet 2 Filed March 5, 1959 Il, ISS

United States Patent Fice 3,112,801, WELL DRILLING APPARATUS Wallace Clark, Tri-County Exploration Co., Inc., 412 Peoples Bank Bldg., Indianapolis 4, Ind., and Albert S. Goldstein, Jr., 1150 Fairfield Ave., Indianapolis, 1nd.

Filed Mar. 5, 1959, Ser. No. 797,455 4l Claims. (Cl. 175--107) This invention relates to well drilling apparatus and more particularly to apparatus of the type wherein the prime mover which drives the drilling bit is located down in the hole being drilled in close proximity to the drilling bit. More particularly the drilling apparatus of the present invention involves the use of a cooperating pair of pumping elements according to the 4invention of R. l. L. Moineau as disclosed in U.S. Patent No. 1,892,217.

The use of this type of prime mover wherein the pumping elements are used as a down-hole drilling motor by forcing a iluid through the elements was first suggested by one of the applicants, Wallace Clark, in his copending application Serial No. 582,0116 filed May 1, 1956, entitled Well Drilling and Earth Boring Apparatus and Method, now United States Patent Number 2,898,087. Other related applications are as follows:

Application Serial No. 683,425, led September 1l, 1957, for a Down-Hole Motor Positioning Device, now United States Patent Number 2,893,693, and

Application Serial No. 731,930; tiled April 30, 1958, for a Method and Means for Governing Fluid Pump in Rotary Well Drilling Rig.

Basically the pump invented by Moineau comprised a stator preferably of resilient material such as rubber and a rotor preferably of stainless steel or other suitable metal arranged to rotate within the stator. 'llhe rotor has a male helical single thread and the stator has a female double helical thread. When the rotor is in engagement within the stator there are provided a series of pockets and when the device is used as a pump by rotating the rotor by means of a prime mover the pockets move in a spiral manner longitudinally of the pump. The rot-or rotates about its own axis and also orbits in a cylindrical path about the axis of the stator. By forcing iluid through the device by means of a pump the apparatus may be caused to operate as a motor whereby to convert the Huid pressure into rotary motion.

It is a characteristic of a pair of elements such as have been described above that the rotor and stator will cooperate equally well regardless of the precise longitudinal alignment of the two. Thus the rotor may be displaced longitudinally within the stator by substantial amounts and if the device is being used'as a pump it will still pump fluids and if it is being used as a motor it will still operate. This characteristic of the Moiueau elements has been known but it has never been suggested that the rotor be deliberately made longer than necessary in order to accomplish any useful purpose.

It is therefore an object of the present invention to provide a down-hole well drilling motor of the type outlined above wherein the rotor element is longer than the stator element so, that it may be moved longitudinally of the stator element a substantial distance, whereby a number of novel advantages may be achieved. The thrust bearings according t-o the present invention can easily be removed Iand replaced, the bearing areas may easily be cleaned or flushed out and relieved of cuttings, automatic take-up for wear is provided and in addition certain shock absorbing effects are obtained.

According to the present invention the bearing races being thinner than the spaces in which they are disposed, are mechanically self-aligned by the grooves on the races in contacting the balls. The bearings are hydraulically centered Within the spaces occupied by them by the swirl- 3,l 12,8% Patented Dec. s, 1963 ing-force caused by the orbital motion of the rotor element, and the gyratory expulsion of flu-id from the pockets formed between the rotor and stator threads. Furthermore the bearings are purged centrifugally by the fluid circulating downward through the upper race, thence thnough the'ball area, and then on around the lower race.

A These objects and others which will become apparent upon reading these specifications or which will be described in greater detail hereinafter we accomplish by v that certain construction and arrangement of parts of which we shall now describe an exemplary embodiment.

Reference is made to the drawings forming a part hereof and in which- FIGURE l is an elevational view of a-drilling apparatus according to the present invention.

FIGURE '2 is a fragmentary longitudinal cross-sectional view on a greatly enlanged scale taken on the line 2 2 of FIGURE l.

FIGURE 3 is a fragmentary longitudinal cross-sectional vieW to the :same scale as FIGURE 2 taken on the line 3-'3 of FIGURE l.

FIGURE 4 is a fragmentary longitudinal oross-sectional view to the same scale as FIGURES 2 and 3 taken on the line 4 4 of FIGURE 1.

FIGURE 5 is a fragmentary longitudinal cross-sectional view to the same scale as FIGURES 2-4 taken on the line 5 5 of FIGURE 1.

FIGUREl y6 is a fragmentary longitudinal crosssectional view on a still further enlarged scale of the upper thrust bearing,

FIGURE 7 is a view similar to FIGURE 6 of the lower thrust bearing of FIGURE 5, and

FIGURE 8 is a cross-sectional view taken along line 3-8 of FIGURE 5.

Briefly in the practice of the invention the rubber or other resilient stator element is molded into a metallictube which may be threaded into the bottom of the drill pipe or into a special coupling member. Into the lower end of the stator holding pipe is threaded a further section of pipe within which the connection .rod structure of the motor is disposed and to the lower end of the last named section of pipe is secured a further section of pipe which carries the bearing struc-ture for the drill.

Referring now particularly to the drawings the lower end of a section of drill pipe is indicated in broken lines at 10. A special coupling member is indicated at 1 1 and the motor casing element is shown at 12. 13 indicates the connecting rod casing port-ion and 14 indicates the casing for the bearing structure. Abit sub is shown at 15 and a suitable drill bit shown in broken lines at 1-6 may be secured in conventional manner to the bit sub 15.

Referring now to FIGURE 2 the coupling member 11 which as can be seen in this figure is hollow, is adapted to be threaded on to the bottom of the drill pipe 10 as indicated at 17. It is provided with threads at its l-ower end whereby the section 1-2 may be threadedly attached as indicated at 1-8.

The section 12 has been referred to as the motor casing. Molded to the inside of the casing 12 is the stator element l19 of rthe drill motor. other suitable resilient material. Within the stator 19 there is disposed the rotor 20 of the motor which rotor is made of stainless steel or other suitable metal. The rotor may be drilled axially as indicated at 21 in broken lines and plugged at its free end as at 21a in order to lighten it if required.

To the lower end of the motor casing 12 there is attached, as by means of the threads 22., the connecting rod casing portion 13.

As its name implies the connecting rod casing portion 13 encloses the connecting rod which is necessary in order This element is of rubber orV that the rotor element 20 may perform its orbital movement. The structure indicated generally at 23 and the similar structure generally indicated at 24 comprise socalled double universal joints. These structures are well known in pumps made according to the invention of yMoineau and since they constitute no part of the present invention they will not be described further. It will be clear that the drill shaft 25 to be described hereafter rotates in bearings on its own axis, which is a Xed axis, while the motor Irotor 20 not only rotates but orbits, and therefore the double universal joints 23 and 24 are necessary to prevent binding.

The structure 24 is connected to the so-called drill shaft 25 by threaded engagement as at 26. The drill shaft is enclosed within a bearing casing element indicated generally at 14, and as shown in FIGURE 5, the casing portion 14 is threaded into the casing portion 13 as at 27. The drill shaft 25 has an axial bore 23, and apertures 29 are provided just below the structure 24 in order to permit the fluid which drives the motor to pass downwardly ythrough the drill shaft 25. Within the bearing casing 14 is provided a -rubber radial bearing 30. This bearing may be configured as shown in FIGURE 8, that is with a hexagonal lcentral opening, or it may be provided with a circular central opening and a series of longitudinal grooves. Such rubber bearings are well known and are often referred to as Cutless bearings. It is by this means that the fluid from the motor reaches the lower thrust bearings to effect the purging and centering action to be described later. In FIGURE this bearing is shown as being pressed in place within a liner 31 and pinned by means of a series of pins 312. It will of course be understood that this radial bearing may be directly molded into the casing element 14 and the liner 31 and pins 32 may be omitted.

Two thrust bearings are provided as will now be described. Considering irst the upper thrust bearing this comprises a lower race 33 which seats on a shoulder provided by the upper end of the casing portion 14 where it is threaded into the portion 13. A series of balls 34 ride in a groove on `the lower race 33 and an upper race 35 also having a ball groove is disposed on top of the series of balls. The upper race 35 bears against a ring 36 which is threaded onto the upper end of the drill shaft 25 as clearly seen in FIGURE 6. Assuming the drilling assembly -to be suspended from the derrick and not resting in the hole on the drill bit the entire assembly comprising the motor rotor 2l), the connecting rod structure and the drill shaft will be supported by the ring 36 bearing against the upper race 35, and through the balls 34 on the lower race 313, which in turn is supported on the shoulder at the top of the casing element 14. It will be observed that a series of plugs may be provided as at 37 located in alignment with the balls 43. This permits removal of the balls 34' for replacement in the event that the races are of very hard steel and the balls wear out while the races do not.

At the lower end of the casing element 14 a flu-ted collar or series of cleats 38 is welded or otherwise suitably secured `to help `guide the bit as seen at the bottom of FIGURE 5 and also in FIGURE 7. The bit sub 15 is threaded onto the lower end of the drill shaft as indicated at 39' and the upper edge of the member 15 provides a shoulder upon which rests the lower race 40 of the lower thrust bearing. A series of balls 41 ride in a ball groove upon the race 40 and the upper race 42 also having a ball groove, rests on the balls `41. Again a series of plugs `43 are provided whereby the balls 41 may be removed for replacement if desired.

It will now be clear that with the parts in position of FIGURE 5 the upper thrust bearing described specifically in connection with FIGURE 6 carries the idling or hanging thrust load. From a consideration of FIGURES 5 and 7 it will be observed that there is a space 44 above the upper race 42, the length of which axially of the device limits the relative axial movement between the rotor and stator of the motor.

When the entire assembly is lowered into a hole and a drilling operation starts, 4the drill bit 16 which is threaded into the sub 15 encounters resistance, and the weight of the drill pipe causes the assembly of the drill bit, the bit sub, the drill shaft, the connecting rod and the motor rotor to move upwand relative to the remaining parts until the upper race 42 abuts the shoulder 45 in the member 14. When this happens of course the load is taken olf the upper thrust bearing, and is now taken by the lower thrust bearing through the member 15 bearing against the lower race 40, with the thrust being transmitted through the balls 41 and the upper race 42 to the shoulder 45. From what was said earlier it will be understood that the drill motor functions equally well regardless of the longitudinal displacement of the rotor with respect to the stator, as permitted by the space 44.

The advantages heretofore outlined and the way in which they are achieved will now become apparent. The two thrust ball bearings can easily be replaced when worn, right on the rig floor without having to lay the tool down. As soon as the bit sub 15 is removed the Whole lower thrust bearing will drop out by gravity and can easily be replaced. As mentioned above if the races are made very hard so that they ontlast the balls the balls can be removed from the side ports which are closed by the plugs 43 or 37. It is then a simple matter to ilush out the bearing area with water and to insert new balls without otherwise disassembling the tool.

The bearings according to the present invention provide for automatic take-up for wear.

From the foregoing description, it will be obvious that during a drilling operation--when the thrust is being taken by the lower thrust bearing member 15, the lower race 40, the balls 41, the upper race 42, and the shoulder 45 the space 44 (shown in FIGURES 5 and 7) will be found between the upper ring 36 and the shoulder of the casing element 14. A portion of the ilu-id being pumped by the motor will then flow through the port 29 and down the shaft 25, and the remainder will ilow through the space between the ring 36 and the casing portion 13 (see FIGURES 4, 5 and 6), past the upper race 35, the balls 34, and the lower race 33, thereby purging these bearings. Similarly, when the tool is lifted by the derrick, the thrust will be taken by the upper set of bearings; and the lower race 40, the balls 41, and the upper race 42 will have the free area 44 in which they may move longitudinally. As was the case with the upper bearing, the fluid from the motor may now flow past them, flushing out any cuttings which may have accumulated.

As will have been noted from a consideration of the figures, and particularly FIGURES 6 and 7, the several races are thinner than the space occupied by them, and they are free of ball cages. This arrangement of the ball bearings makes them self-aligning, and they can move so that the balls will line them up in seeking their positions in the grooves of the races. The upper bearings will be hydraulically centered by virtue of the gyrating pressure stream set up by the helically moving pockets created between the stator and rotor. It will be of course be understood that the rotational movement of the drill shaft 25 imparts a similar gyrating movement to the fluid pumped from the motor as it emerges from the rubber radial bearing 30. As was true of the upper bearings, this gyrating pressure stream will serve to hydraulically center the lower bearings.

The above described construction also adds to the selfcleaning properties of the bearings. Since the balls are loose, and not confined in the conventional cages, the balls may move with respect to each other and thus push chips aside into the cleansing stream of fluid passing through the bearings.

Bearings as described above may of course have utillity in other well drilling apparatus and apart from well d. w ...4. a

drilling apparatus as herein disclosed. For example they may be used in connection with apparatus such as turbines, electric motors and other types or iluid driven motors, wherein longitudinal movement may be provided below the prime mover, as for example by means of splines or other mechanism. Thus the unique advantages of the bearing may still be utilized.

There is still a further advantage attained by the present invention. During a drilling operation the hydraulic pressure on the rotor will be transmitted downward, and the bit and connecting parte will be kept riding ahead on the formation which is being drilled, and the thrust will not be taken entirely by the thrust bearing, which will be relieved by the amount of the hydraulic downward thrust on the rotor plus the weight of the rotor This hydraulic pressure will act as a shock absorber in retarding the upward movement of the bit and associated parts and therefore the lower thrust bearing will be protected from undue shock oi impact. Additionally the members dd, 4l and l2 will act as a resisting piston plunger in the area d4, thus adding to the shock absorbing capacity. It on the other hand the drill pipe is lowered faster either intentionally, or inadvertently as a result of the normal bounce experienced during a drilling operation, these parts will be protected by hydraulic cushioning. This advantage, which is or great importance is achieved as a result ot the relative longitudinal movement between the rotor and stator of the motor, which is provided for by this invention and which so far as we know has never been deliberately provided in any such device.

lt will be understood that numerous variations and modifications may be made without departing from the spirit of the invention. Thus, for example, the ball bearings may be replaced by other types of bearings such as iiat discs of metal or composition clad metal. Thus it will be clear that the speciiic bearings disclosed for the thrust bearings as well as the specific bearing disclosed for the radial bearing do not constitute limitations upon the present invention. We therefore do not intend to limit ourselves otherwise than as set forth in the claims which follow.

Having now fully described our invention what we claim as new and desire to secure by Letters Patent is:

l. A well drilling assembly comprising a motor casing section adapted to be secured to the lower end of a string of drill pipe, a connecting rod casing section secured to the lower end of said motor casing section, and a bearing casing section secured to the lower end of said connecting rod casing section, a hydraulic motor adapted to be driven by a stream of lluid under pressure comprising a stator of resilient material bonded within said motor casing section and having a double internal helical thread, a radial bearing mounted in said bearing casing section, said bearing casing section having an internal annular shoulder near its lower end, a hollow drill shaft disposed within said bearing casing section for rotation in said radial bearing, a hollow bit sub secured to the lower end of said drill shaft and providing an annular shoulder, a thrust bearing surrounding said drill shaft between said shoulders with substantial longitudinal play, means for introducing the iluid from said motor into said thrust bearing, said bearing casing section at its upper end providing a shoulder, a retaining ring secured to said drill shaft adjacent its upper end, a thrust bearing surrounding said drill shaft between said last named shoulder and said retaining ring with substantial longitudinal play, means for introducing the liuid from said motor into said last named thrust bearing, said thrust bearings each comprising an upper and a lower race, and a series of balls therebetween, said races being provided with ball grooves and being free of ball cages, whereby said races may move relative to each other within the area of longitudinal confinement, said bearings thereby being capable of purging themselves oi foreign particles, a metallic rotor having a single helical thread disposed in operative relationship within said stator, and a connecting rod connecting said rotor and drill shaft, wherehy the motor rotor, connecting rod, dril shaft and bit sub, as a unit, may move a substantial distance longitudinally of said stator and casing section, with one or said thrust bearings being operative to take the thrust in one direction at one limit oi such movement, and the other of said thrust bearings being operative to take the thrust in the opposite direction at the other limit of such movement.

2. A device according to claim 1, wherein the races are provided with ball grooves and are thinner than the areas in which they slide longitudinally whereby they are capable of self-alignment and centering.

3. A structure according to claim 1 wherein said bit sub is threadedly secured to the lower end of said drill shaft whereby upon removal oi` said bit sub said lower bearing races and balls may be removed by gravity for replacement.

4. A structure according to claim 1 wherein at least one hole is provided through said casing opposite said lower thrust bearing and at least one hole is provided through said casing opposite said upper thrust bearing said holes being aligned with the position of the respective series of balls when said device is freely suspended and said holes being or a diameter such that said balls may be removed through said holes for replacement, and means for plugging said holes.

References Cited in the tile of this patent 

1. A WELL DRILLING ASSEMBLY COMPRISING A MOTOR CASING SECTION ADAPTED TO BE SECURED TO THE LOWER END OF A STRING OF DRILL PIPE, A CONNECTING ROD CASING SECTION SECURED TO THE LOWER END OF SAID MOTOR CASING SECTION, AND A BEARING CASING SECTION SECURED TO THE LOWER END OF SAID CONNECTING ROD CASING SECTION, A HYDRAULIC MOTOR ADAPTED TO BE DRIVEN BY A STREAM OF FLUID UNDER PRESSURE COMPRISING A STATOR OF RESILIENT MATERIAL BONDED WITHIN SAID MOTOR CASING SECTION AND HAVING A DOUBLE INTERNAL HELICAL THREAD, A RADIAL BEARING MOUNTED IN SAID BEARING CASING SECTION, SAID BEARING CASING SECTION HAVING AN INTERNAL ANNULAR SHOULDER NEAR ITS LOWER END, A HOLLOW DRILL SHAFT DISPOSED WITHIN SAID BEARING CASING SECTION FOR ROTATION IN SAID RADIAL BEARING, A HOLLOW BIT SUB SECURED TO THE LOWER END OF SAID DRILL SHAFT AND PROVIDING AN ANNULAR SHOULDER, A THRUST BEARING SURROUNDING SAID DRILL SHAFT BETWEEN SAID SHOULDERS WITH SUBSTANTIAL LONGITUDINAL PLAY, MEANS FOR INTRODUCING THE FLUID FROM SAID MOTOR INTO SAID THRUST BEARING, SAID BEARING CASING SECTION AT ITS UPPER END PROVIDING A SHOULDER, A RETAINING RING SECURED TO SAID DRILL SHAFT ADJACENT ITS UPPER END, A THRUST BEARING SURROUNDING SAID DRILL SHAFT BETWEEN SAID LAST NAMED SHOULDER AND SAID RETAINING RING WITH SUBSTANTIAL LONGITUDINAL PLAY, MEANS FOR INTRODUCING THE FLUID FROM SAID MOTOR INTO SAID LAST NAMED THRUST BEARING, SAID THRUST BEARINGS EACH COMPRISING AN UPPER AND A LOWER RACE, AND A SERIES OF BALLS THEREBETWEEN, SAID RACES BEING PROVIDED WITH BALL GROOVES AND BEING FREE OF BALL CAGES, WHEREBY SAID RACES MAY MOVE RELATIVE TO EACH OTHER WITHIN THE AREA OF LONGITUDINAL CONFINEMENT, SAID BEARINGS THEREBY BEING CAPABLE OF PURGING THEMSELVES OF FOREIGN PARTICLES, A METALLIC ROTOR HAVING A SINGLE HELICAL THREAD DISPOSED IN OPERATIVE RELATIONSHIP WITHIN SAID STATOR, AND A CONNECTING ROD CONNECTING SAID ROTOR AND DRILL SHAFT, WHEREBY THE MOTOR ROTOR, CONNECTING ROD, DRILL SHAFT AND BIT SUB, AS A UNIT, MAY MOVE A SUBSTANTIAL DISTANCE LONGITUDINALLY OF SAID STATOR AND CASING SECTION, WITH ONE OF SAID THRUST BEARINGS BEING OPERATIVE TO TAKE THE THRUST IN ONE DIRECTION AT ONE LIMIT OF SUCH MOVEMENT, AND THE OTHER OF SAID THRUST BEARINGS BEING OPERATIVE TO TAKE THE THRUST IN THE OPPOSITE DIRECTION AT THE OTHER LIMIT OF SUCH MOVEMENT. 